Pyridoxal phosphate

Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), also known as vitamin B6 is a coenzyme involved in many reactions in amino acid metabolism, including transamination, deamination, and decarboxylation. PLP also participates in the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine, and gamma-aminobutyric acid (GABA).

Structure and Function

PLP is the active form of vitamin B6, which comprises three natural organic compounds, pyridoxal, pyridoxine and pyridoxamine. PLP binds to enzymes through a Schiff base linkage to a lysine residue on the enzyme. This covalent bond functions to decrease the pKa of the enzyme-bound lysine residue, facilitating enzyme catalysis.

Role in Enzyme Function

PLP is a versatile catalyst, acting as a coenzyme in a multitude of reactions including decarboxylation, deamination and transamination. PLP-dependent enzymes are primarily involved in the biosynthesis of many important neurotransmitters such as serotonin, dopamine, and GABA.

Deficiency and Toxicity

Deficiency of PLP can cause a variety of symptoms, including dermatitis, depression, confusion, and convulsions. Toxicity is rare, but can cause nerve damage and photosensitivity in some individuals.

See Also

• Vitamin B6
• Coenzyme
• Neurotransmitter
• Serotonin
• Dopamine
• GABA

References

Pyridoxal phosphate Resources
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